eigen_csv.hpp

#ifndef EIGEN_CSV_H
#define EIGEN_CSV_H

#include <Eigen/Dense>

#include <cfloat>
#include <fstream>
#include <iomanip>
#include <sstream>
#include <string>
#include <vector>

namespace EigenCSV {

template <typename T> void write(const Eigen::DenseBase<T>& A,
        const std::string& filename) {

    using namespace std;

    ofstream file;

    file.open(filename);

    file << setprecision(DBL_DIG);

    for (int i = 0; i < A.rows(); i++) {
        for (int j = 0; j < A.cols(); j++)
            file << A(i,j) << ',';
        file << endl;
    }

    file.close();

}


template <typename T> void write(const Eigen::DenseBase<T>& A,
        const std::vector<std::string>& header,
        const std::string& filename) {

    using namespace std;

    ofstream file;

    file.open(filename);

    for (unsigned int i = 0; i < header.size(); i++)
        file << header[i] << ',';
    file << endl;

    file << setprecision(DBL_DIG);

    for (int i = 0; i < A.rows(); i++) {
        for (int j = 0; j < A.cols(); j++)
            file << A(i,j) << ',';
        file << endl;
    }

    file.close();

}

template <typename T> void read(const std::string& filename,
        bool header, bool resize, Eigen::DenseBase<T>& A) {

    using namespace std;

    ifstream file;

    file.open(filename);

    string line, cell;

    if (header) {
        getline(file, line);
    }

    vector<vector<double>> vals;

    while(getline(file, line)) {

        stringstream str(line);

        vector<double> valr;

        while(getline(str, cell, ','))
            valr.push_back(stod(cell));

        vals.push_back(valr);

    }

    int rows, cols;

    if (resize) {
        rows = vals.size();
        cols = vals[0].size();
        T& B = (T&) A;
        B.resize(rows, cols);
    } else {
        rows = A.rows();
        cols = A.cols();
    }

    for (int i = 0; i < rows; i++)
        for (int j = 0; j < cols; j++)
            A(i,j) = vals[i][j];

}

}

#endif